Electric recording apparatus



y 1952 H. A. STAMPER 2,596,446

ELECTRIC RECORDING APPARATUS Filed NOV. 12, 1948 INVENTOR 'H. A. STAMPER ATTORNEY Patented May 13, 1952 ELECTRIC RECORDING APPARATUS Hamilton A. Stamper, Los Angcles, Califi, assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application November 12, 1948, Serial No. 59,565

This invention relates to marking on paper by an electric discharge and has as an object to provide a practicable and inexpensive apparatus for electrically marking ordinary paper.

It is common in various recording instruments, such as are used in depth recording and picture transmission, to drag an electrically conductive stylus across a special paper, which responds to an electric discharge from the stylus to make a visible mark.

The present invention provides for electrical recording on ordinary paper by producing the electrical discharge, not between the stylus and the paper, but between the stylus and a special electrode positioned close to the paper surface. In practice, it is convenient to pull the paper (in the form of a tape) between a guide rod and a roller of carbonaceous material, the tape being bent around the guide rod so that a channel or groove is formed between the paper on one side and the carbonaceous roller on the other side. The stylus is moved along this groove in contact with the paper and with the roller, and the marking potential is applied between the stylus and roller. Because of the high contact resistance between the stylus and roller, the application of the potential produces a flash or are therebetween which smudges the adjacent portion of the paper (which is separated from the flash by less than the width of the stylus wire).

A full understanding of the invention may be had from the following detailed description which refers to the drawing.

In the drawing,

Fig. 1 is a front elevation of a portion of a depth recorder incorporating the invention, the case being shown in section;

Fig. 2 is a horizontal section, looking upward in the plane IIII of Fig. 1; and

Fig. 3 is a schematic diagram showing the electrioal circuit of the system.

Referring to Figs. 1 and 2, there is shown a paper tape l upon which a depth record is to be made. This paper is fed in the direction indicated by the arrow in Fig. 2, from a spool that is not shown, around a guide rod II which changes the direction of flow of the paper substantially 90. Thereafter, the paper is drawn across a back plate I 2, and the portion of the paper in the stretch extending in front of the plate I2 visibly displays the record that has been formed on the paper tape.

Marks are recorded on the paper tape by a stylus l3 that rides in a groove or channel [4 that is defined between the convex portion of the paper I0 where it is wrapped around the 8 Claims. (Cl. 346-74) guide rod II, and a conductive element l5 which is juxtaposed to the rod H on the other side of the paper. The conductive element 15 is in the form of a cylinder which is supported for free rotation in bearings IE0 at its opposite ends. The member l5 may consist of a metal core I5a surrounded by an envelope l5b of some relatively resistive material such as a compressed mixture of graphite and clay, or the like. The member l5 may be grounded by a brush [6 which bears against its periphery and is connected to the frame ll.

The mounting of the stylus 13 does not constitute a part of the present invention, but may consist of a carriage l8 pivotally supported on opposite ends of a pivot member l9 that extends through a rubber block 20 mounted upon a belt 2|. The belt 2| is stretched between pulleys 22 and 23 respectively, one of which (23 in this instance) is driven by a constant speed electric motor 24. The stylus I3 is mounted upon one side of the carriage l8, and a. brush 2'! is mounted upon the opposite side of the carriage l8' and rides across a starting segment 28, and then across a conductive track or segment 29, the brush 21 remaining in contact with the segments 28 and 29 throughout the traverse by the stylus [3 of the paper tape Ill.

The operation of the system will now be explained in connection with the schematic diagram of Fig. 3. Let it be assumed that the motor 24 is operating at constant speed to drive the belt 21 in such direction as to periodically sweep the stylus l3 through the channel M defined between the paper tape, and the conductive element [5, and simultaneously causes the brush 2'! to traverse the segments 28 and 29. As the brush 2! passes from the starting segment 28 onto the segment 29, it momentarily connects them together. Referring to Fig. 3, this permits application of a positive potential from the plate 3! of a condenser 32, through a conductor 33, through the segment 29, the brush 21, the carriage l8, and the stylus l3, thence from the stylus to the conductive member IE, to ground. The electrode 3! of the condenser 32 is normally charged to a high potential, being connected to the positive terminal of a battery 35. through a reactance element 35 and a resistor 35. The described discharge from the stylus [3 tothe conductive member 15 produces a baseline 39 on the paper tape I0. At the same time, the high potential of the segment 29 is applied to the starting segment 23 and thence over a conductor 40 and through a condenser 4| to the control grid 42 of a tube 43, causing the latter to become conductive and permit discharge of a condenser 44, which shocks an oscillation circuit consisting of a reactance 45, the distributed capacitance 46 of the transmission line 41, and the internal capacity 48 of a transducer 49. A damped train of oscillations is set up in the circuit including thereactance 45, the transmission line 41 and the transducer 49, energizing the transducer to send out sonic waves of corresponding frequencies, which waves are reflected from an object, such as the bottom of a body of water. The reflected wave is received by the transducer, converted into electrical impulses, and transmitted over, the transmission line 41 to the reactor 45 from which it is applied through a resistor 50 to the input of an amplifier 51. connected through the condenser 32, the seg: ment 29, the brush 27, and the carriage 18, to the stylus [3, so that theimpulse is discharged through thestylus H to the conductive--mem-- ber 15, causing another mark'52 to beproduced on the tape H), which mark is indicative-of the distance from the transducer 49 to the point of reflection.

The marking of the paper may result ironra smudging eilect produced by the discharge betweenthestylus l3 and the'conductive member l5 because'ofthe close-proximity'oi the paper tape illto the discharge. Thus, as shown in Fig; 2, the sty1us-l3 rests against the paper l= consist of equal parts of cuprous iodide and mercuric chloride in light varnish-which turn from redto brown between 130 F. to-160 'F.

The dischargeproduces a certain wearing'or disintegration of the surface otthe conductive member l5, and forthis'reason it" is desirable, to form this member as acylinder and permit it'to be rotated by movement of the paper tape ID therepast, so that a new surface is being-continually presented to the stylus'l3.

A carbonaceous material has been found in practice to be suitable for, the conductive ele ment l5, because it produces a slight are or burning effect atthe time of discharge, without overheating the stylus and causing rapid wearing away thereof. However, whilecarbonaceous materials have been found especially satisfactory in practice, the invention is not'limited to such materials. It appears that the'important essential characteristic of the member 15 is that it have a relatively-high resistivity compared to the stylus I3 so that the electrical discharge will produce a substantial heating of the surface of the member [5 at its point of contact with the stylus [3.

Although for the purpose of explaining the invention, a particular embodiment thereofhas been shown and described, obvious modifica- Lions will occur to a person skilled in the art,

The output of the amplifier 5] is.

Thestyluswears in service, sothatit and I do not desire to be limited to the exact details shown and described.

I claim:

1. Electric recording apparatus comprising: a record blank and means for supporting it and moving it through a predetermined path; a contact member independentv of said record blank and of electrically conductive material having a stylus-contacting surface extending transversely across said path parallel to and in close proximity to one face of said record blank; an electrically conductive stylus on the same side of saidrecord blank as said contact member and means\ for traversing said stylus along said stylus-contacting surface of said contact member; and means for applying a marking potential between said stylus and said contact member to produce a recording current between the stylus and the contact member.

2. Apparatus according to claim 1 in which said-contact member has high resistivity relative to said stylus, whereby flow of-said recording current in said stylus and contact member at the point of contact thereofby'said'stylusgenerates' more heat in said contact member than in said stylus.

3. Apparatus-according to claim 1 in which saidcontact-member is of'carbonaceousmaterial.

4.. Apparatus according to claim' 1 in' which" said contact member is of curved" cross section substantially in contact with said record blank,

wherebydt defines-with said record blame a channel for guiding saidstylus.

5; Apparatus according to claim 4 said contact member is cylindrical.

6. Apparatus according to claim- 5 said cylindrical contactmember is' supported.

7. Apparatus'according to claim fiinwhich said rotatable cylindrical contact member is.in contactwith said record blank whereby it is re,- tated byrnovement' of the recordblank there.- past."

8. Apparatus ccording to claim 1' in which said means for supporting said record blank comprises: a guide member extending. parallel toand'on-the opposite side of said record blank from said-contactmember, and'means for drawin which in which rotatably ing' said record blank between said; guide and.

contact members and around-said guide member away from saidcontact member, that portion of said record blank in closest proximity, to said stylus-contacting surfaceof' said. contact member being backed by saidguide member.

HAMILTON A. S'IAMPER.v

REFERENCES CITED The following references. are -of recordinthe file of this patent:

UNITED STATES 'PATENTS Number Name Date 2,141,975 Finch Dec. 27, 1938 2,173,113 Hogan'et al; Sept. 19, 1939" 2,212,970- Finch Aug. 2711940 2,355,502 Barton Aug. 8;.1944. 2,384,515 Wise Sept. 11', 1945". 2,425,003 Potter Aug. 53,1947 2,437,242 Cole1et a1 Mar. 9; 1948' 

